The aims of this study are to analyse the concrete data of Japanese dialects, and theoretically generalize the changes of garammar.Through the research following two points are cleared up.1. Formation and the changing way of each grammatical elements of Japanese dialects.2. General theory of changing mechanism of grammatical forms of Japanese dialects.After ordering the preceding researches, analysing methods ware made up, we collected the concrete grammatical data of Japanese dialects thorough field works and Grammar Atlas of Japanese Dialects (GAJ).We researched and analysed 1. application of the methods of geolinguistic way to grammatical fields, 2. analysis of grammaticalization of case markers, 3. analysys of grammaticalization of topical markers of Hokuriku dialects, 4. descriptions of final particles of Yarnagata dialects, 5. formation way of case markes in Tohoku dialects, 6. analysis of grammaticalization of conjunctions, 7. analysis of formations of potentials in Kyushu dialects, 8. analysis of past recollectives, 9. descriptions of final particles in Hokuriku dialects.We generalized each individual dialectal datum and phenomenon, and made up the general theories of diachronic changes of grammar of Japanese dialects.